Correlation between arrested secondary plasmodesmal development and onset of accelerated leaf senescence in yeast acid invertase transgenic tobacco plants

Mature leaves of a transgenic tobacco plant ( Nicotiana tabacum L var. Samsun, line A41-10) that constitutively express a yeast-derived acid invertase gene develop symptoms which are characterized by the presence of greenish-yellow and green sectors in the same leaf, and onset of early, leaf senescence. Previous studies indicated that invertase activity was two- to threefold higher in the greenish-yellow sectors than in the green sectors. Our structural analyses revealed that development of secondary plasmodesmata, via modification of existing primary plasmodesmata, between mesophyll cells was inhibited severely in the greenish-yellow sectors, but only marginally in the green sectors. In contrast, the structure and function of primary plasmodesmata in the same symptomatic sectors remained unaltered as determined by structural and dye coupling studies. It is hypothesized that secondary plasmodesmata differ from primary plasmodesmata in having special abilities to traffic information molecules to coordinate leaf development and physiological function(s). Arrest of secondary plasmodesmal development by high invertase activity in the transgenic tobacco leaf may have prevented this type of trafficking and hence resulted in early leaf senescence. The results also indicate that the yeast acid invertase-expressing tobacco may provide an effective experimental system for the molecular characterization of cellular mechanisms that regulate the development, function, and possible turnover of secondary plasmodesmata.     

A well-characterized polycistronic-like gene expression system in yeast

Efficient expression of multiple genes is critical to yeast metabolic engineering for the bioproduction of bulk and fine chemicals. A yeast polycistronic expression system is of particular interest because one promoter can drive the expression of multiple genes. 2A viral peptides enable the cotranslation of multiple proteins from a single mRNA by ribosomal skipping. However, the wide adaptation of 2A viral peptides for polycistronic-like gene expression in yeast awaits in-depth characterizations. Additionally, a one-step assembly of such a polycistronic-like system is highly desirable. To this end, we have developed a modular cloning (MoClo) compatible 2A peptide-based polycistronic-like system capable of expressing multiple genes from a single promoter in yeast. Characterizing the bi-, tri-, and quad-cistronic expression of fluorescent proteins showed high cleavage efficiencies of three 2A peptides: E2A from equine rhinitis B virus, P2A from porcine teschovirus-1, and O2A from Operophtera brumata cypovirus-18. Applying the polycistronic-like system to produce geraniol, a valuable industrial compound, resulted in comparable or higher titers than using conventional monocistronic constructs. In summary, this highly-characterized polycistronic-like gene expression system is another tool to facilitate multigene expression for metabolic engineering in yeast.     

Thermostability enhancement of polyethylene terephthalate degrading PETase using self- and nonself-ligating protein scaffolding approaches

Polyethylene terephthalate (PET) hydrolase enzymes show promise for enzymatic PET degradation and green recycling of single-use PET vessels representing a major source of global pollution. Their full potential can be unlocked with enzyme engineering to render activities on recalcitrant PET substrates commensurate with cost-effective recycling at scale. Thermostability is a highly desirable property in industrial enzymes, often imparting increased robustness and significantly reducing quantities required. To date, most engineered PET hydrolases show improved thermostability over their parental enzymes. Here, we report engineered thermostable variants of Ideonella sakaiensis PET hydrolase enzyme (IsPETase) developed using two scaffolding strategies. The first employed SpyCatcher-SpyTag technology to covalently cyclize IsPETase, resulting in increased thermostability that was concomitant with reduced turnover of PET substrates compared to native IsPETase. The second approach using a GFP-nanobody fusion protein (vGFP) as a scaffold yielded a construct with a melting temperature of 80°C. This was further increased to 85°C when a thermostable PETase variant (FAST PETase) was scaffolded into vGFP, the highest reported so far for an engineered PET hydrolase derived from IsPETase. Thermostability enhancement using the vGFP scaffold did not compromise activity on PET compared to IsPETase. These contrasting results highlight potential topological and dynamic constraints imposed by scaffold choice as determinants of enzyme activity.     

A Meaningful Attempt: Applying Dielectric Barrier Discharge Plasma to Induce Polarization of Macrophages

Macrophage polarization plays an important role in many macrophage-related diseases. This study was designed to preliminarily explore the effects of dielectric barrier discharge (DBD) plasma on the polarization direction and cell activity of macrophages with different phenotypes (ie, M0, M1, and M2). The M1 macrophage marker inducible nitric oxide synthase (iNOS) and M2 macrophage marker cluster of differentiation 206 (CD206) were detected by western blot (WB). The effects of DBD plasma on macrophage viability were analyzed by using a cell counting kit-8 detection kit. M0, M1, and M2 macrophages exhibited a decrease in iNOS expression and an increase in CD206 expression after the DBD plasma intervention. Additionally, the decrease in macrophage viability remained non-significant after initiating the intervention. DBD plasma can promote the transformation of M0 and M1 macrophages to M2 macrophages, and can further enhance the expression of the M2 macrophage phenotype marker CD206. Our study not only demonstrates the potential therapeutic value of DBD plasma for macrophage-related diseases, but it also provides a new direction for research to improve the treatment of macrophage-related diseases. © 2023 Bioelectromagnetics Society.     

屎肠球菌对斑节对虾肠道代谢组学及炎性因子的影响

【背景】屎肠球菌(Enterococcus faecium)作为乳酸菌属的潜在益生菌,因其具有良好的生物学特性在动物养殖中应用广泛,但是屎肠球菌对肠道代谢组学的研究很少。【目的】以斑节对虾为试验动物,初步探究屎肠球菌R8对肠道代谢组学及炎性因子的影响,为屎肠球菌作为益生菌在对虾养殖中的应用提供理论基础。【方法】将400条斑节对虾随机分配,设计饲料中屎肠球菌添加量分别为107、108、109 CFU/g的3个试验组,不添加屎肠球菌为对照组进行试验,养殖周期为28 d。养殖周期结束后测定斑节对虾免疫球蛋白M (immunoglobulin M,IgM)、对虾酚氧化酶(phenoloxidase,PO)、白介素6 (interleukin 6,IL-6)、补体片段3a (complement fragment 3a,C3a)的活性含量并运用LC-MS代谢组学研究肠道内源代谢物的变化,分析差异代谢物和相关的代谢通路。【结果】添加屎肠球菌对斑节对虾炎性因子有积极的影响,增加了斑节对虾体内免疫球蛋白IgM、对虾酚氧化酶、补体片段3a的含量,降低了其体内IL-6的含量,对肠道差异代谢物的分析发现,对...     

油藏注入水靶向脱硫潜力的高温脱硫菌群富集驯化

【背景】海上油田见聚后产出水硫化物超标,影响到注聚水的配聚黏度,采用生物脱硫时,由于常规除硫菌难以适应除油后产出液的高温,使得脱硫效果不佳。【目的】分析海上采出液水处理过程的菌群结构,明确生物处理各节点的菌群构成变化;开展耐高温脱硫菌驯化筛选,获得耐高温的高效脱硫菌。【方法】采集来自胜利油田海三站的水样,以16S rRNA基因高通量测序技术分析样本菌群结构,并分别在不同温度(55、60和65℃)下的无机富集培养基中进行多轮转接驯化,结合常压室温等离子体(atmospheric and room temperature plasma, ARTP)诱变技术筛选获得耐高温的脱硫菌群,采用宏基因组测序技术分析富集菌群的组成,并测定其脱硫能力。【结果】处理前的采出液水样含有较多的嗜热菌和硫酸盐还原菌,如Thermodesulfovibrio、Pseudothermotoga、Thermolithobacter、Fervidobacterium、Thermovenabulales和Pseudomonas;以厌氧气浮除油工艺处理的出水中,嗜氢菌属(Hydrogenophilus)成为最主要的优势菌,...     

Biochemical and Physiological Responses of Cucumis sativus Cultivars to Different Combinations of Low-Temperature and High Humidity

Low-temperature and high humidity are typical environmental factors in the plastic tunnel and solar greenhouse during the cold season that restricts plant growth and development. Herein, we investigated the impact of different combinations of low-temperature and high humidity (day/night: T1 15/10 °C?+?95%, T2 12/8 °C?+?95%, and T3 9/5 °C?+?95%) along with a control (CK 25/18 °C?+?80%) on cucumber cultivars viz: Zhongnong37 (ZN37: resistant) and Shuyanbailv (SYB: sensitive). The low-temperature and high humidity stresses increased electrolyte leakage (EL), malondialdehyde (MDA), hydrogen peroxide (H₂O₂) and intercellular concentration of carbon dioxide (Ci), and reduced morphological indices, relative water content (RWC), net photosynthesis rate (Pn), stomatal conductance (Gs), transpiration rate (E) and leaf pigments in both cultivars as compared to control (CK). Superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR) were decreased in cv. SYB under stress conditions as compared to cv. ZN37. Low-temperature and high humidity treatments showed an increase in proline and soluble protein content in cv. ZN37 as compared to cv. SYB. Abscisic acid (ABA) and jasmonic acid (JA) were augmented while indole-3-acetic acid (IAA), zeatin (ZT), zeatin riboside (ZR), and gibberellic acid (GA) were decreased in both cultivars. Under T3 (9/5 °C?+?95%), Pn, protoporphyrin, and ZT were extremely decreased by 71.3%, 74.3%, and 82.4%, respectively, in cv. SYB compared to control. Moreover, principal component analysis (PCA) based on physiochemical traits confirmed that cv. ZN37 had the strongest correlation with antioxidant enzymes, proline, and soluble protein content than cv. SYB under low-temperature and high humidity treatments. Our results suggest that a stress-tolerant cultivar mitigates stress damage in cucumber transplants by regulating photosynthetic efficiency, antioxidant capacity and hormonal profile when compared to a stress-sensitive cultivar.

     

生物活性物的生物制造：现状、挑战和发展趋势

生物活性物的生物制造是指利用包括细胞、微生物和酶在内的生物系统生产具有生物活性的天然或合成分子的过程。这些分子可用于制药、化妆品、农业和食品工业等领域,对提高生命质量、延长生命长度具有重要意义。在合成生物学和自动化等技术的推动下,生物制造领域迅速发展,为创造新产品和替代传统产品提供了绿色可持续的生产模式,为生物经济的增长、创新作出了重要贡献。本文结合生物活性物研发及生产情况,简要梳理并分析了国内外生物活性物的现有市场和未来发展。生物制造作为一种绿色、可持续的生产方式,将在生物经济发展中持续发挥重要作用。     

陕北黄土高原蒿属植物的分类与分析

陕北黄土高原有蒿属植物30种1变种,居该地产种子植物属中所含种数的首位。所产蒿属植物在不同的植被带中梯度变化明显,替代现象显著。在生态类型上,旱生类型从南向北递增,中生类型从南向北递减。在区系组成上可分为6种分布区类型,即:我国特有分布,3种;温带亚洲分布,14种1变种;北温带及中亚分布各4种;旧世界温带分布,3种;东亚分布的2种。可见陕北黄土高原蒿属植物种类丰富,梯度变化明显,旱化现象显著,地理成分复杂,但以温带亚洲分布类型为主,兼有其它成分,属典型的温带性质。     

蛋白质结构成对比较的新方法

介绍一种蛋白质三维结构的快速比较方法.此方法毋需初始联配,而能自动寻找和智能迭代.利用本程序对珠蛋白、丝氨酸蛋白酶、天冬氨酸蛋白酶、钙结合蛋白和溶菌酶作了系统的结构比较,取得了满意的结果.本文也讨论了衡量联配结果好坏的要素问题.